Refrigeration and water condensate removal apparatus

ABSTRACT

An air cooling and water condensate removal panel has at least two interconnected capillary systems close to a plate having cooling means for removing heat from the plate. The first capillary system exists in a porous, thin outer layer having a very fine capillary structure which presents a cool, wettable surface upon which moisture in the air condenses. The outer layer is maintained cool by the cold plate. The condensate water soaks through the thin porous outer layer and is drawn into the interconnected second capillary system. The second capillary system is substantially coarser than the first system to cause the water to be drawn away more rapidly than the condensate can form upon the outer surface. The water in the coarser capillary system is drawn into a discharge pipe, preferably by employing a pump to maintain a mild vacuum in the pipe.

" United States Patent Jacob Sept. 16, 1975 REFRIGERATION AND WATER 3,383,878 5/1968 Booth 62/272 CONDENSATE REMOVAL APPARATUS 3,394,756 7/1968 3,420,069 1 /1969 [76] Inventor: Carlyle W. Jacob, 118 Presidents 3,490,718 1/1970 Ln., Quincy, Mass. 02160 3,541,807 11/1970 Henderson 62/272 [22] Filed: June 24, 1974.

. Primary ExaminerWilliam J. Wye [21] Appl. No.: 482,793

[52] US. Cl. 62/272; 62/93; 62/100; 62/268; 62/281; 62/315; 62/316; 62/467; 165/1 10 [51] Int. Cl. F25d 21/00 [58] Field of Search 62/281, 316, 315, 100, 62/268, 271, 272, 283, 93, 94, 467; 165/110, 1 11 [56] References Cited UNITED STATES PATENTS 2,478,617 8/1949 Anderegg 62/271 3,132,989 5/1964 Stevenson. 62/281 3,168,137 2/1965 Smith 165/110 3,170,512 2/1965 Smith 165/110 3,197,973 8/1965 Rannenberg 62/467 3,359,753 12/1967 Fiedler 62/93 Related US. Application Data Continuation-impart of Ser. No. 370,392, June 15, 1973, which is a continuation-in-part of Ser. No. 247,449, April 28, 1972, abandoned, which is a continuation-inpart of Ser. No, 10,824, Feb. 12, 1970, abandoned.

Attorney, Agent, or FirmWolf, Greenfield & Sacks [5 7] ABSTRACT An air cooling and water condensate removal panel has at least two interconnected capillary systems close to a plate having cooling means for removing heat from the plate. The first capillary system exists in a porous, thin outer layer having a very fine capillary structure which presents a cool, wettable surface upon which moisture in the air condenses. The outer layer is maintained cool by the cold plate. The condensate water soaks through the thin porous outer layer and is drawn into the interconnected second capillary system. The second capillary system is substantially coarser than the first system to cause the water to be drawn away more rapidly than the condensate can form upon the outer surface. The water in the coarser capillary system is drawn into a discharge pipe, preferably by employing a pump to maintain a mild vacuum in the pipe.

79 Claims, 12 Drawing Figures FIG. I

PATEHTEMEPIWS 3,905,203

SHEET 1 UF 4 7 FIG. I

G. 3 INVENTOR CARLYLE W. JACOB ATTORNEY PATEHTEDSEP 1 6191s 3; 905,203

sum 2 05 1 FIG. 4

INVENTOR CARLYLE W. JACOB BY ATTORNEY PATENTEU SEP 1 5 FIG. 11

FIG. 12

REFRIGERATION AND WATER CONDENSATE REMOVAL APPARATUS This application is a continuation-in-part of Ser. No. 370,392, filed June 15, 1973; and which is a continuation-in-part of Ser. No. 247,449, filed April 28, 1972, abandoned; and which is a continuation-in-part of Ser. No. 10,824, filed Feb. 12, 1970, abandoned.

SUMMARY OF THE INVENTION This invention relates in general to improvements in air cooling and water condensate removal systems. More particularly, the invention relates to improved means for collecting and conducting away the water that condenses out of the air upon the cold surfaces of the cooling system.

OBJECTIVES OF THE INVENTION The primary objective of the invention is to provide apparatus for cooling the air while causing the water which condenses upon the cooling surfaces to be removed. It is a further object of the invention to provide cooling and dehumidifying apparatus which can be incorporated into a structure so as to become part of its ceiling or walls. In the employment of the invention, it is preferred that the cooling surfaces be located on the ceiling or upper part of the walls of the room or container where the warmer air is encountered. An additional objective of the invention is to provide cooling and dehumidifying apparatus that is quieter in operation than conventional air conditioning apparatus. A further object is to provide a cooling surface for the inside of a refrigerator with means for removing the water than condenses thereon THE INVENTION The invention resides in an air cooling and water condensate removal apparatus that is preferably embodied in the form of a thin flat panel having one face presenting a fine, wettable, toothed or porous surface and having its other face thermally insulated. In the panel is a cold plate having means, such as a circulating fluid coolant, for removing heat from the plate. The wettable surface is the exposed face of a thin toothed or porous layer or sheet having capillary openings that is maintained cool by the cold plate to cause moisture in the ambient air to condense upon that surface. Because the layer has capillary openings, the condensate water soaks through the thin outer layer and enters an adjacent second capillary system. The second capillary system is much coarser than the system of fine capillaries in the outer layer. The water entering the coarser system, therefore, can proceed quickly through that system to a discharge tube or pipe which drains the coarse system. To facilitate the drainage of the second capillary system, a mild vacuum is preferably maintained in the discharge tube. The thin outer layer, may also include finely toothed areas that conduct water laterally to capillary openings that connect to the adjacent secnd capillary system.

THE DRAWINGS The invention, both as to its construction and its mode of operation, can be better understood from the following exposition, when it is considered in conjunction with the accompanying drawings in which:

FIG. 1 is a cross-sectional view in elevation of the invention embodied in the form of a flat panel;

FIG. 2 is a top plan view of the flat panel in which A--A indicates the parting plane along which the sectional view of FIG. 1 is taken;

FIG. 3 depicts, in cross-section, a form of the invention having drainage tunnels extending into the coarser porous layer;

FIG. 4 illustrates the cross-sectional aspect of another embodiment of the invention in which the coarse capillary system is formed by a network of grooves in the face of the cold plate;

FIG. 5 is a top plan view taken along the parting plane 55 in FIG. 4;

FIG. 6 is an elevational cross-sectional view depicting the preferred embodiment of the invention; and

FIG. 7 is a detailed showing of a capillary plug that may be employed in the FIG. 6 embodiment.

FIG. 8 is an elevational cross-section view depicting another embodiment of the invention;

FIG. 9 is a top plan view taken along the parting plane 9-9 in FIG. 8;

FIG. 10 is a detailed view of one of the perforations shown in FIG. 8 embodiment; and

FIG. 11 is an elevational cross-sectional view depicting another embodiment of the invention;

FIG. 12 is an elevational cross-sectional view depicting still another embodiment of a cold plate.

THE EXPOSITION FIGS. 1 and 2 depict the invention embodied in the form of a flat panel which is intended to be affixed to the ceiling of a room or other structure in the area to be cooled. The panel can, if desired, be mounted upright against a wall but the ceiling location is preferred where the tendency of the warmer air to rise is relied upon to cause air circulation rather than employing a blower or other mechanical means to move the air. In the panel, a plate 1 constituted of a material having good heat conductivity properties, such as aluminum or other metal, is cooled by a cold fluid flowing through the tubing 2 which is in contact with the plate to facilitate transfer of heat from the plate. The fluid may be any of the coolants commonly employed in conventional refrigeration systems. The means for cooling the plate need not necessarily be of the type employing a fluid and it is contemplated that where economic considerations permit, thermoelectric or other means may be used to replace or augment the fluid cooling system.

In lieu of employing the plate 1 which acts, in a sense, to diffuse the cold, the cooling tubes can be so closely spaced that a separate plate is not required. However, to reduce weight and avoid the larger pump that would be required to force the coolant through the additional tubing, use of a cold plate with more widely spaced tubes is preferred. The efficiency of the plate and tube system can be increased somewhat by forming internal passages in the cold plate itself as conduits for the coolant instead of employing tubes that are separate from the plate.

The tubing 2 and cold plate 1, as shown in FIG. 1, are protected by a heat insulative shield 3 which inhibits the flow of heat into the cooling system from the backside of the panel. Beneath cold plate 1 are two porous layers 4 and 5. The outer porous layer 5 is preferably very flne grained with a relatively smooth exposed surface 6 that wets easily. The porous layers 4 and 5 act to soak up water that condenses out of the air onto the exposed cold surface 6, as that water, unless it isremoved, collects and forms drops on the cold surface which drip downfrom the panel. To remove the water that condenses on the cold surface 6, a suction pump 7 is provided to maintain a vacuum within a discharge tube or pipe .8 communicating with the inner porous layer 4. The pump maintains a mild vacuum to cause water-soaking, through porous layer into layer4 to be drawn into the discharge tube and from thence the effluent is vented to a drainage system.

The outer porous layer 5 preferably has a fine textured surface-6 which permits it to be readily cleaned of contaminants. It has been found that over a period of-time;, air borne contaminants, particularly those of an oily nature such as the vapors given off in the preparation of fried foods, fumes from oil burners, tobacco smoke, etc.,- can cause the-formation of an oily film which, though it may be no more than a few millionth of an inch in thickness, nonetheless destroys or materially inhibits. the wetting of the exposed surface of the panel by condensed water andprevents the water from soaking through the finely pored outer layer. The water condensing upon the oily film tends to form globules that drop off instead of spreading out and soaking into the porous layers. Also, the surface 6, being finely textured, does not present sharp points or small protrusions which in collaboration, with the oily film can promote the formation of water globules. Further, the smooth textured surface generally has a grater aes thetic appeal than a coarse surface with large pores. This is particularly true where the panel is used on the ceiling. I

A further advantage in'covering the inner coarse porous layer 4 with a very fine textured outer layer 5 is that it enables higher vacuums to be built up in the coarse layer 4 than in the case where there is no outer finely. porous layer 5. With the employment of the outer layer 5 the suction produced by the pump 7 will not be localized in the areaof the layer 4 that is near the ,pump but will instead spread out in considerable strength to all portions of the layer 4, even'those portionsof layer 4 that are far removed from the pump. Thus panels very extensive in area can be built and be made to operate effectively.

Inner/porous layer 4, is, in relation to layer 5, quite coarse with large capillary passages that permit the water entering from the outer layer 5. to be rapidly drawn in the lateral direction toward the discharge tube 8. Where-the panel is provided with only one porous layer havinga fine or medium fine porosity, it has been found that if the panel is of appreciable area,- the resistance to fluid. flow in the lateral direction toward the dischargetube is so great that the layer may not transport the condensate-to the discharge tube as rapidly as the water condenses upon the exposed cold surface areas farthest removed from the discharge tube. By increasing the thickness. of the solitary layer, the lateral transportv capacity of the layer in enhanced. However, the great extra thickness that is needed for the porous layer substantially reduces the thermal efficiency of the cooling panel since the flow of heat is then across a greater volume of the porous material. Increasing the thickness of thelayer tends, therefore, to thermally insulate-.the cold plate from the ambient air it is desired to cool. By employing two layers of different porosity in; accordance with the teaching of the invention, greater thermal efficiency than can be obtained with a solitary layer-is achieved and removal of the condensate .water is:assured even where the air is excessively humid. Y

The pump 7 considerably enhances the ability of the panel to remove the water condensate. However, the pump, although very desirable, particularly where strong conditions of humidity are expected to be encountered, is not always essential. Where the discharge tube 8 is composed of a bundle of capillary tubes or is filled with a porous, wettable, substance such as finely ground glass or glass fibers, then water soaking into the porous layers is drawn by capillary action into the discharge tube and thence flows by gravity into a sink or drainage receptor. To improve the'coupling between the relatively small opening in the discharge tube 8 and the thin inner porous layer 4, the marginsof the porous layer 4 can be greatly increased in thickness, as indicated in FIG. I, to form a drainage gutter or pathway or channel 4A from which the water is drawn into the discharge tube 8. The water soaking through layer 5 into inner layer 4 flows laterally into the marginal drainage channel 4A and thence is drawn into discharge drainage tube 8.

The marginal drainage channel 4A is preferably filled with the same porous material as that used for the inner layer 4. Because of the large cross-sectional area of the marginal drainage channel, there is but little frictional resistance to the passage of water in the channel and, consequently, the pressure drop around the drainage channel is slight. The channel acts, in essence, like a continuation of the discharge tube circumscribing the margin of the inner porous layer 4. The marginal drainage channel, of course, need not extend on all four sides of the panel. Where the marginal drainage channel is only on the side of the panel adjacent tube 8, the efficiency in the removal of water is still better than is the case where no drainage channel is provided. Where the panel is of large area, the drainage channel 4A, in addition to extending around the perimeter of the panel, may also have some branches that extend into the interior of the panel. A wall 9 that is preferably heat insulative extends around the perimeter of the panel thus enclosing the sides of the panel and adding mechanical strength to the panel.

The inner porous layer 4 and the marginal drainage channel 4A may be constituted of portland cement which has been aerated to cause many large capillary passageways to form in the hardened material. Alternatively, glass fibers or coarse sand bound together with a small amount of portland cement may be employed to form the coarse porous inner layer and marginal drainage channel. Porous sheets made of sintered sand or carborundum, such as are used in abrasive wheels and knife sharpening blocks, may also be used in the panel.

The outer porous layer 5 may be composed of a portland cement mixture which is fine grained. Pure portland cement which is preferably of the variety that is white in color may be advantageously used for this purpose. Where pure portland cement is used to form the outer layer 5, it is made into a paste having more water than is needed for the hydration of the cement and the paste is applied over the coarse layer 4 to form a very thin coat. The excess water causes minute cavities or voids to be left between the cement particles. The pure portland cement coat, when solidified, is easily wet and the many fine capillaries formed by the interconnected cavities or voids cause the water to soak through the thin coat into the underlying coarser layer 4.

The outer porous layer 5, in addition to having a fine texture, should, for most applications, be smooth and level. However, for decorative effects, it may be desired to have the exposed surface of the panel present a mottled, uneven or roughened appearance, or even to incorporate ornamental substances such as small multicolored stones into the surface. Where the ornamentation or roughness does not materially impede the basic cooling and water removal functions of the panel, the surface of the panel can be altered to provide the desired ornamental appearance. The essential aspect of the panel resides in the coarse inner capillary layer or passageway network with large low resistance pores or passageways that permit rapid conduction of the condensate water laterally to the discharge tube and in the contiguous outer layer which has a very fine textured capillary system and which provides both a wettable and easily cleanable exposed cooling surface.

A rough appearing outer surface can be produced by cementing many coarse grains of sand, or even bits of fine crushed rock to the outer surface of the fine porous layer 5. It should be understood that although a panel having a cold plate covered only by a coarse capillary layer 4 may be rough appearing and satisfy any decorative requirements for a rough appearing panel this one layered panel cannot function satisfactorily as a dehumidifying and air cooling device. The large exposed pores in the coarse layer 4 would collect dirt and foreign matter too readily and are difficult to clean. A finely textured outer porous layer 5 is much easier to keep clean, and thus makes a good protective cover and dirt shield for the inner coarse layer 4. The outer finely textured layer 5 may have small ornamental stones or bits of crushed rock cemented to or embedded in its surface but with a cleaning cloth or brush one can easily clean around these stones. However, if the coarse layer 4 is unprotected by a finely porous protective covering seal and the coarse pores in this layer 4 become contaminated with dirt and foreign matter then it is very difficult, even with the aid of a good brush, to clean out the deep pores, particularly the deep down under the surface pores. Furthermore, these large deep pores are much worse as dirt collectors than the fine pores in the outer protective layer 5. Even though large grains of sand or ornamental stones of various types may be successfully incorporated in the outer finely textured layer 5 to thereby produce a mottled, roughened or otherwise decorative surface it is still preferable to have the outer surface of layer 5 smooth and uncluttered by any additional objects such as coarse grains of sand, stones, etc.

However, there is one type of covering material for i this outer layer 5 that can be quite advantageous. If a very thin hard, essentially solid, white plastic sheet perforated with many small holes spaced one-eighth inch apart is bonded to the underside of the outer porous a white paint on the underside of layer 5 in a manner such that many tiny spots spaced about one-eighth inch apart on the under surface of the layer 5 will not be covered by the paint. These spots correspond to the perforations in the plastic sheet discussed above. It is through these tiny openings in the coating of white paint that water can be pulled into the panel. This multitude of tiny openings may be distributed in either a random or regular pattern over the surface of the coating. Also if the openings are tiny enough, such as microscopic openings, they may be spaced much closer together than one-eighth inch. The printed plastic coating with its many small openings or aperatures although it may be thinner than the perforated plastic sheet has the same function as the sheet and is generally considered equivalent to the perforated sheet. The plastic covering with its many small openings can be considered to be a part of the porous layer 5.

FIG. 3 illustrates a modified form of the FIG. 1 panel, In the modified embodiment, a tubular capillary drainage tunnel 10, communicating with the discharge tube 8, extends into the inner porous layer 4. Preferably there should be large numbers of these drainage tunnels in the porous layer 4 with the tunnels interconnecting with each other at least at their terminal ends, so as to form a network of tunnels. This network should communicate with the discharge tube 8. These capillary drainage tunnels, which may also be referred to as capillary drainage channels, act as low resistance passageways for the removal of water from the porous layer 4. The tunnels 10 may have a larger cross-section than that shown in FIG. 3 to increase their drainage capabilities. For ease in fabricating the panel the capillary drainage tunnels are preferably located at the top of the inner layer 4 so that they are in contact with the cold plate. They may furthermore have a generally rectangular rather than a round cross-section. The marginal drainage channel 4A of the FIG. 1 panel may then be eliminated as its function is performed by the network of long capillary drainage tunnels 10. The modified panel of FIG. 3 thus has three capillary networks: first, a very fine capillary network in the outer porous layer 5; second, a coarser capillary network in the inner layer 4; and third, a still coarser capillary network formed by the long tunnels 10. The outer, very fine porous layer 5 provides a smooth outer surface upon which the condensate forms and soaks through. The next layer 4, having a coarser capillary structure, facilitates the rapid transfer of the condensate water in the upwards direction as well as laterally. Instead of having to flow laterally toward the marginal drainage 4A as in the FIG. 1 embodiment, the water in the FIG. 3 panel embodiment, need flow upwards and laterally only until it encounters the network of long capillary tunnels 10. The tunnels, being of larger size, then offer decreased resistance to the water flow and, consequently, the water flows rapidly toward the discharge tube 8. The very fine capillary system of the outer layer 5 does not offer appreciable resistance to the absorption of water because the outer layer is thin and the water need move only through the thickness of the layer to encounter the coarser capillary system in the inner layer 4. Where the outer layer 5 is a few hundredths, or even a few thousandths of an inch or less in thickness, the pressure drop in the water passing through the layer is quite small. In the inner layer 4, the capillary passages must be appreciably larger as the water may have to move a distance of several inches to encounter a drainage tunnel and unless the passageways are relatively large the pressure drop may be so great as to slow the rate of water removal to the point where the condensate that has formed on the outer surface cannot be entirely accommodated.

The drainage tunnels or channels may, as mentioned above, be located next to the heat absorbing plate so that each tunnel is bounded on its upper side by the heat absorbing plate and its remaining three sides by the porous layer 4. Drainage tunnels or channels in the porous layer will still be referred to as drainage tunnels or channels in or embedded in the porous layers even though each individual tunnel or channel is bounded on only three of its sides by the porous layer. These tunnels, even though bounded on only three of their sides by the porous layer, can still very efficiently drain the porous layer of water. The drainage capabilities of these tunnels, particularly if they are closely spaced to one another, can be very effective so that the porous layers 4 and 5 can sometimes be combined in a single fine grained porous layer without unduely impairing the usefulness of the cooling panel. However the combination of the two porous layers 4 and 5 is still preferred. A very thin perforated plastic sheet may often be advantageously incorporated in or made to replace the outer porous layer 5.

FIGS. 4 and 5 depict an embodiment of the invention in which the panel has a smooth fine grained porous layer 5 having an exposed surface 6 and tubing 2 is employed to cool a thermal heat absorbing and diffusing plate, as in the FIG. 1 embodiment. The diffusing heat abosrbing or cold plate 11, however, as indicated in FIGS. 4 and 5, has thin grooves 12 on its face which interlace to form a grid network which communicates with the discharge tube 8. A mild suction is maintained in the discharge tube by the pump 7. The panel may be fabricated by filling the grooves in the face of plate III with a wax, plastic or other filler substance that is not affected by water but is nevertheless easily dissolved by other solvents. The face of the plate is then coated with a portland cement paste, as in the fabrication of the FIG. 1 panel. After the cement coat has hardened, the filler is dissolved and removed from the grooves. Care must be taken applying the cement layer to insure that the portion of the layer over the grooves is free of wide cracks, large holes or other defects. Unless the grooves are completely covered by a fine porous layer which is free of large openings, the maintenance of a suitable vacuum within the capillary system formed by the grooves will be impeded.

An alternate procedure to insure a more positive coverage of the grooves by the cement is to have the grooves thin but deeply cut and then to have the porous cement layer partly extend up into the grooves and thus firmly anchoring the cement layer into the cold plate and insuring a complete thick positive porous covering over the grooves. The grooves in the cold plate 11 may be milled out ofa flat heat conductive plate such as aluminum, or strips of a material having at least a resonably good heat conductivity may be cemented onto a flat aluminum plate at spaced intervals to form slots or drainage channels at the surface of the plate. These channels will functionally be identical to machined grooves even though the cemented strips may have a different composition from the flat plate to which they are cemented. Thus, the word grooves will be considered to have this broader meaning.

When the panel is in operation, water vapor in the air condenses upon the surface 6 of the finely porous layer 5 5 where it soaks into the layer and spreads laterally and upwardly toward the grooves 12 in the face of the cold plate. The condensate water is sucked into the grooves and then rapidly moves to the discharge tube 8. The grooves 12, preferably, have a smaller cross-section than that of a droplet of water so that a droplet fills the cross-sectional area of the groove and is therefore readily sucked along the groove toward the discharge tube. By way of example, the grooves may be onesixteenth inch in width, although somewhat larger or smaller grooves also can provide the desired result. The grooves 12, in essence, function as a coarse capillary network or layer that drains the finer capillary system of layer 5. The grooves may take an infinite variety of network configurations. The network, for example, may consist of a multitude of parallel grooves with no interlacing connecting passageways between them except at their discharge ends where they join onto the discharge tube. On the network, for example, may have the configuration of the veins in a leaf where the veins all lead to a common artery. The grooves may be spaced one or two inches apart or they may be so closely spaced so as to approach the spacing of grooves in a machinists file.

One advantage in having the coarse capillary network actually inside the cold plate is that the fine outside capillary network, such as layer 5, can then be in actual contact with the cold plate. If this outside layer 5 is quite thin, then the thermal insulation between the cold plate and the adjacent air it is desired to cool will be small and the thermal efficiency of the cooling system will be high. However it should be noted that the porous layer 4 in the FIG. 1' and 3 panels may be filled with large numbers of small balls or chips or other particles having a high thermal conductivity such as aluminum or brass chips. These chips will increase the thermal conductivity of the entire porous layer 4 so that the FIG. 1 and 3 panels will be thermally more efficient and cool the air more rapidly.

Inasmuch as all objects or structures near the cooling tubes 2 and the cold plate 11 tend to become cold, it is desirable to protect such objects from condensation. Accordingly, the thermal insulation 3 is, in the FIG. 4 panel, extended around the edges of the cold plate 11 and the outer porous layer 5 overlaps the extended insulation. Thus, water that condenses upon the extended insulation is absorbed into the layer 5 and is conducted to the discharge tube through the grooved network in the plate 11.

The finely porous layer 5 covering the surface of the cold plate 11 can in some cases be dispensed with. If in addition to the deep grooves 12 in the surface of the cold plate 11 the remaining portions of the outer surface of the plate are finely toothed or otherwise grooved then condensate water will flow along the toothed surface to the deep grooves 12 where it will be sucked away. The deep grooves 12 should also, of course, be covered over by a finely porous cement mixture to seal their outer side. As previously outlined this porous mixture may be made to extend partly up into the grooves 12 so that the outer surface of the cold plate 11 may, if desired, be quite flat with no raised areas over the covered grooves 12. The finely toothed surface may, by way of example, be produced by cementing a single layer of fine grains of sand to the outer surface of the plate 11. As an alternate procedure the outer surface of the cold plate may be pitted or toothed by chemical etching treatments. The aluminum plate may even be first painted white before being pitted. The surface of a suitable layer of paint can be much more stable chemically and have better water retention properties than an untreated aluminum surface whose wettability can vary greatly with time because of corrosion. The pitting may be accomplished by sand blasting with fine particles. Whether the outer surface of plate 11 is a porous layer or a toothed layer it is still essentially a capillary layer and as such will conduct water readily in a lateral direction.

Another alternate proceedure in the construction of the FIG. 4 type of panel is to substitute a thin perforated sheet of plastic or metal for the porous layer with the perforated sheet being firmly bonded to the grooved cold plate 11. The grooves may, by way of example, by about one-sixteenth inch in width and the raised portions of the cold plate between the grooves about one-eighth inch or three-sixteenth inch in width. The perforations should be very small and may be distributed at random over the surface of the perforated sheet or they may be distributed according to some patterm such as positioning them only over the grooves. The outside surface of this perforated sheet should preferably be finely toothed to facilitate the lateral movement of water condensate but even if it is not toothed a large drop of water on its surface will contact at least one or more of the perforations over a groove and be sucked away, provided the grooves are reasonably closely spaced to one another and of course the perforations also. If this close spacing does exist then the water droplets will be drawn up into the perforations and grooves before they can become large and heavy enough to drop off the perforated sheet. Grooves and perforations spaced about one-eighth to threesixteenths inch apart are usually close enough to catch and draw away all of the water droplets on the outside surface of the perforated sheet. Of course if the outside surface of the perforated sheet is toothed then the perforations and grooves may be more widely spaced.

Although this perforated sheet comes under the broad classification of a porous or capillary material or layer or sheet since it does have small holes that penetrate the sheet and these holes will permit fluids to pass through the sheet, nevertheless, this perforated sheet is a very special kind or species of porous material that differs from the customary or conventional type of porous material in that it is not honeycombed with pores. The customary porous layer or porous sheet is internally honeycombed with vast numbers of closely spaced interconnecting pores, as for example, a sheet of blotting paper, a thin block of a carborundum or alundum knife sharpening stone, a thin sintered metal block or a portland cement layer that is fabricated in a manner to produce many fine interconnecting voids within the layer. In a perforated sheet the holes or perforations pass directly through the sheet without undue wandering around laterally inside the sheet. A perforated sheet may be fabricated by piercing a solid sheet with many small holes either mechanically or by chemical etching methods. As is known in the art, a solid plastic sheet may be subjected to ionic bombardment or to nuclear bombardment followed by chemical etching to form very fine perforations in the sheet. Raw plastic may even be cast or otherwise molded in a suitable mold to produce a plastic sheet having the desired perforations moulded therein. Or, the sheet may be a thin metal sheet that has been perforated with an ultrafine needle or even chemically etched to produce the perforations. There should of course be a considerable distance between adjacent perforations. Thus the perforations in a perforated sheet will not interconnect as in the customary type of porous sheet. The perforations if not fine enough might even be plugged with a fine porous material such as a special portland cement mixture that will harden into a porous solid. These porous plugs will further impede the flow of air through the perforations and into the panel.

One of the very desirable features of a perforated sheet is that it is much easier to keep clean than the customary porous sheet particularly if the distance between adjacent holes in the perforated sheet is large compared to the size of the holes. In this latter case most of the surface area of the sheet will be the surface of a solid material which is easy to keep clean. The perforated sites will constitute only a relatively small percentage of the total surface area of the sheet. These perforated sites can still be kept clean but not nearly as easily as the remaining areas between perforations. This is true irrespective of whether or not the perforations are plugged with a porous material or are unplugged and open. The perforated sheet might even be coated over its entirety by a very thin layer of a finely porous paint and if this overall porous layer is quite thin then this coated perforated sheet will still be easier to maintain in a clean condition than the customary relatively thick non-perforated porous sheet having vast numbers of closely spaced interconnecting pores in depth such as a sheet of alundum. The reason for this is that the pores in a thin finely textured porous coating or layer covering a perforated sheet are not nearly so numerous and deep down as the pores in the customary relatively thick porous sheet unsupported by a perforated sheet such as an unsupported porous portland cement sheet which must be relatively thick for structural strength. Dirt that has penetrated into deep down pores tends to become entrapped there and is more difficult to remove than the dirt that has settled in surface pores or pores close to the surface. Thus a perforated sheet, particularly one in which the perforations are small compared to the distance between perforations, will be easier to keep clean than the customary finely porous sheet or layer unsupported by a perforated sheet and the customary finely porous sheet or layer will be easier to keep clean than the customary coarse porous sheet or layer. The perforations in a perforated sheet may be positioned in some evenly spaced geometric pattern or they may be much more randomly positioned. Particularly if they are randomly positioned there may be some of the perforations that are very close together. In referring to a perforated sheet or plate having perforations which are small compared to the distance between perforations one is referring, of course, to the average sized perforation and also to the average distance between perforations.

Another advantage of a perforated sheet is that it is more rugged than the customary simple porous sheet and ,is thus better able to withstand the disruptive forces of freezing water without fracturing. A perforated sheet is mostly solid material and this solid material around the perforations is often strong enough to contain the expansive forces of water freezing within a perforation. The customary porous sheet or layer being very porous with interconnecting pores throughout its entirety is more apt to structurally deteriorate when water within its many pores freezes.

Layer bridging the grooves in the FIG. 4 panel should as previously mentioned be a material containing fine pores to permit the seepage of water up into the grooves. The word material is here used broadly to mean not only a shapeless substance but also a shaped member such as a sheet. Even cloth is often called a material and cloth does have the configuration of a sheet. Or a sheet of plywood used in the construction of a house is frequently referred to as a construction material. Thus the material containing the fine pores and bridging the grooves in the FIG. 4 panel may be, for example, a finely porous portland cement layer or a perforated metal or plastic sheet having small perforations which may be further constricted by plugging the perforations with a finely textured porous substance.

The perforations in a perforated sheet or plate should normally, for simplicity, be constructed with a round circular cross-section. However they can be constructed with a long narrow cross-section such as a slit or slot. In this latter case it is the narrow dimension of the slot that is being referred to when the statement is made that the perforations are small compared to the distance between perforations; or, on an area basis, the cross-sectional areas of the perforations should be small compared to the intervening non-perforated areas on the perforated plate.

The term perforations or perforated plate refer to the appearance and function of the plate rather than the method of manufacture. For example if one wished to produce a heat absorbing plate having long thin perforations such as a slot herein one could employ manufacturing techniques that differ from the method of simply punching out the slots, If, for example, one wished to produce a heat absorbing plate having parallel rows of long thin perforations such as slots on the exposed surface of the plate, and also suitable long drainage channels in the plate beneath the slots, one could first groove out a plate somewhat as in the heat absorbing plate 11 in FIG. 4. Then a thin perforated metal sheet in which the perforations were parallel rows of long narrow slots that were cut by a saw in the plate could be bonded to the grooved side of the plate with each slot being directly over one of the grooves. These slots might even run the entire length of the heat absorbing plate 11. This same structure could also be constructed as a monolithic structure by extruding aluminum through suitable dies. The extrusion would then comprise a heat absorbing plate, including the appropriate parallel rows of drainage channels and long narrow slots. The drainage channels would be completely enclosed by the aluminum within the aluminum plate except for the long very narrow slit-like openings that communicate with the exposed surface of the plate thereby permitting condensate water on the exposed surface to seep through the slots and into the drainage channels and be drawn away.

A somewhat similar type of structure might even be made by manipulating a thin sheet of aluminum in a sheet metal bending press and other metal shaping machines until a structure having the necessary slots and drainage channels was produced.

Thus in this application the term perforation or perforated plate or sheet is intended to have a broader meaning and to include plates with long narrow slits or slots or aperatures in them even though the slots were produced by extrusion and other types of manufacturing processes the differ from the conventional stamping, punching, or boring operations. The term perforation in a plate is used in this application to indicate an opening, hole, orifice or aperature that penetrates the surface of a plate without wandering around inside the plate like the pores in a carborundum block. Furthermore, the perforation should not be a dead ended hole but should serve as a connecting link between two portions of the plate. Thus a perforation may extend from the exposed surface of a plate to a drainage channel within the plate thereby permitting water condensate on the surface of the plate to seep into the drainage channel and be drawn away. A perforation normally would penetrate into a plate until it either passed through the plate or else reached a cavity in the plate such as a drainage channel. Thus it is the surface of the plate that appears to be perforated or pierced or the otherwise penetrated, with the perforation in many cases not passing all the way through the plate but only to a cavity within the plate. The perforation may of course be blocked by a blocking member such as a porous plug or a rubber pad, etc.

The term perforated plate or sheet as used in this application is not intended to include a woven material such as a woven screen A woven screen is a material with holes or pores therein but it is not a perforated plate or sheet.

A woven screen is structurally not very strong and furthermore has a very uneven surface that is not easy to keep clean. The holes in a screen are not small compared to the distance between holes thus adding to the cleaning problems. For a perforated plate or sheet to be properly suited for this invention the area of the plate occupied by the holes should be small compared to the areas of the plate between the holes. Then the plate can be kept clean looking and furthermore if the perforated plate is a heat absorbing plate there will be more area of the plate exposed to the air to more rapidly cool the air.

In FIG. 12 is shown a cross-sectional view of a heat absorbing plate 41 in which the drainage channels 43 are embedded in the plate. The plate may be fabricated by an extrusion process These drainage channels communicate with the exposed surface 42 of the heat absorbing plate 41 through the perforations 44. The drainage channels are relatively thin and run the length of the plate. Likewise the perforations which are very narrow slits run the length of the plate. The relative widths of the drainage channels and slits need not be as indicated in FIG. 12, which is simply a schematic representation. The slits may be much wider than that shown or much narrower so that the two opposing sides of the slits may actually contact each other at least at intervals along the lengths of the slits. If the two opposing sides of a slit are close enough together to contact each other then the slit become a crack. However condensate water can still seep through this crack if suitable other conditions exist such as an adequate suction in the drainage channels. A crack is still considered to be a perforation if it allows water to seep through. The

drainage channels should all be made to interconnect by means ofa cross-channel near their terminal ends so that they can all communicate with the discharge tube.

A slit-like perforation in a plate can be considered to be a series of aligned small holes that may have, for example. a circular or square cross-section with the holes in an aligned string of holes so closely spaced the adjacent holes in the string overlap thus causing the string of small holes to become a narrow slit. Thus one can look upon a slit-like opening as being a single long narrow perforation or as being instead a series of overlapping very small perforations with each small perforation having a generally round of squareish crosssection.

As is brought out in the US. Pat. No. 3,420,069 issued Jan. 7, 1969 to F. W. Booth, it is possible to design a cooling system that utilizes cold water as the coolant as causing this cold water to circulate to a reduced pressure in the condensate water drainage passageways rather than through special cooling tubes, such as the tubes 2. Thus the inner coarse capillary passageways would be made to double as both cooling tubes and as condensate water drainage passageways. However, using the water drainage passageways for this dual function has some major shortcomings. For one thing the inner capillary passageways would have to be considerably enlarged to carry the additional water coolant. They would probably, for practical purposes, have to be enlarged to the point where they cease to be capillary passageways. A cold water coolant would required an even larger duct system than the standard freon coolant would since the cold water cannot be supplied at as low a temperature as the freon. Also, with a cold water coolant flowing the in the inner passageways there would always be the great danger that with any shut down or malfunction of the pumps or other components of the cooling system vast quantities of cooling water would drip down from the panel into the room below. Thus panel design that separates the cooling system from the water condensate drainage system is considered to have, in most applications, considerable merit over a cooling panel which uses common ducts within the panel for both the coolant and the water condensate. The tubing for the cooling fluid, such as tubing 2, and the water condensate passageways and conduits may be next to and touching each other but as long as the actual cooling fluid and the water condensate are confined within their own separate duct systems to that there is no general mixing of the cooling fluid and water condensate then the two systems will be considered in this application to be separate from each other.

FIG. 6 depicts an embodimentof the invention which is a modification of the FIG. 1 panel. In the FIG. 6 embodiment, the inner porous layer 4 of the FIG. 1 panel has been replaced by a capillary layer existing above a perforated sheet or plate 13 having many holes in it. A heat absorbing or cold plate 1 is disposed above the perforated plate and a slight separation between the two plates is maintained by spacer 14. The separation may be in the order of 0.003 inch or 0.005 inch, although it can be larger. To promote thermal conduction between the plates, spacers 14 should have good thermal conductivity. The spacers may be wider than those shown to increase the thermal conduction. The

spacers divide the space between the plates into numerous flat capillary passages but those spacers must not block offthe perforations in plate 13 to any marked extent. Where the lower surface of cold plate ll has protrusions or where that surface is grooved or corrugated to form ribs, then the protrusions 0r ribs act as the spacing elements. In a similar manner the perforated plate may have protrustions on its upper side which act as the spacing elements. The essential feature of the construction employed, whatever it is, is that is provides capillary passageways between the plates. These capillary passageways correspond to the capillary network provided by the inner porous layer 4 in the FIG. 1 embodiment. The undersurface of perforated plate 13 in the FIG. 6 embodiment is covered by the finely textured outer layer 5. Water which condenses on the exposed surface 6 is drawn laterally and upwardly through layer 5 to the perforations in plate 13. At the perforations, the condensate is drawn upwardly and into the capillary network between the plates 1 and 13 from whence it is sucked to discharge tube 8 by the mild vacuum maintained in the tube by the pump 7.

It may be noted that while the outer porous layer 5 must conduct water in the lateral as well as the perpendicular direction, that layer may still have a quite fine capillary structure, because the lateral paths, although being considerably longer than the perpendicular paths, are still relatively short. For example, where the perforations in plate 13 are spaced at 1 inch intervals, the longest lateral conduction path in the outer layer is only one-half inch.

In the panels shown in FIGS. 1 and 3, the porous cement layers 4 and 5 on the undersurface of the cold plate 1 are generally applied in two separate steps. First the coarse layer 4 is applied and after that has set the outer fine grained layer is applied over the hardened coarse layer 4. However in some cases the two cement layer 4 and 5 can be applied in a single operation. A portland cement mixture can be made to harden with a quite porous interior but with an outer skin that is unusually dense and compact with pores that are much finer in grain than the pores under the skin in the interior of the layer. A compound layer of this type may sometimes be effectively used in the various panels shown in this application wherever it is advantageous to have a dense finely textured layer over a layer having coarser pores. Even in the panels shown in FIGS. 4 and 6 there can be advantages in having the porous layer 5 constructed as a compound layer as just described with the interior of layer 5 being relatively fine textured but with the outer surface of layer 5 comprising an unusually fine textured, hard and dense skin.

In lieu of employing the outer layer 5 in the FIG. 6 panel, the undersurface of perforated plate 13 may be the exposed cold surface of the panel. Where that plate is so used, the underside of the plate is preferably toothed or grooved or laced with ruts to provide lateral capillary conduction paths for the condensate. However, the layer 5, because it contains capillary passages in some depth can be more effective in conducting water laterally than a simple toothed surface. However deep toothing such as deep thin ruts or grooves on the undersurface of the perforated plate can also be quite effective in conducting water laterally and when a plate is so grooved the perforations in the plate can be very widely spaced from one another without adversely affecting the water absorbing capabilities of the plate.

There is one special case where the lateral conduction ability of the exposed cold surface is not too critical to preclude use of the underside of plate 13 for that purpose even where the underside is smooth and noncapillary. The special case occurs where the perforations in plate 13 are so closely spaced that adjacent perforations are not separated by more than one-eighth inch for example in any direction. Where the perforations are that closely spaced, droplets of water forming on the exposed cold surface of plate 13 cannot exceed one-eighth inch in diameter without encountering an aperture in the plate through which the droplet would be drawn. The spacing between perforations must be small enough to preclude a droplet from attaining the size necessary to cause it to drip from the exposed cold surface. That spacing, of course, is dependent in part upon the material of which plate 13 is constituted and the finish of the exposed surface. However, even in the special case, it is still preferable to employ the porous outer layer or a toothed surface to diminish or eliminate the appearance of droplets on the panels surface.

Assuming the water condensate on the surface of the FIG. 6 panel reaches a perforation in the plate 13, it is desirable that wettable capillary passageways exist up through the perforations to cause the water to rise. Where the perforation is slender and has wettable sides, the perforation itself acts as the capillary tube. However, the capillary action can be improved by employing larger perforations which are plugged with a substance that is eminently porous and wettable, such as a portland cement mixture or certain ceramics.

FIG. 7 is an enlarged view of a perforation having a porous, wettable plug 15. The plug not only completely fills the perforation in plate 13 but also has an enlarged head 15A which bridges the gap between plate I and 13. Unless that gap is bridged, water may rise to the top of the plug and then cease to flow, particularly where the vacuum is weak in the space between the plates and the cold plate is widely spaced from the top of the plug. Causing the plug to bridge the gap between the plates, insures the existence of a continuous path for the water all the way to cold plate 1 and the water in the head of the plug is then situated to permit it to be drawn laterally toward the discharge tube 8. The lateral movement is partly due to the mild vacuum in the passageway between the plates and partly to the action of the plug it self in distributing the water into the enlarged head.

In the FIG. 6 embodiment, the entire space between the cold plate 1 and perforated plate 13 can be filled with a porous, wettable capillary material such as fine glass filaments. The filler is particularly desirable if the spacing between the plates is relatively large. The use of the filler descreases the need of having the porous plugs in the perforated plate extend all the way to the cold plate.

It is especially important where the cooling panel is to be used in the horizontal position illustrated in FIG. 6, that the spacing between cold plate 1 and perforated plate 13 not be so great as to prevent surface tension and capillary forces from insuring that the water in the space will bridge the gap between the plates. Where the spacing is too large, water which is sucked into the space through the perforated plate may simply lay stagnant as a thin layer on the upper surface of the perforated plate with a layer of air over the water layer. If such occurs, the water cannot be sucked laterally to the low pressure discharge tube 8 until the water level rises enough to displace the air layer and contact cold plate 1. Furthermore, having a pool of water upon the perforated plate is particularly undesirable when the operation of the panel is closed down by removing the power to the suction pump and to the cooling apparatus. On terminating operation of the panel, the water on the perforated plate may, because the vacuum no longer is maintained, seep through the perforated plate and drip into the space below. Where the spacing between the plates is small, no appreciable amount of water can be accomodated on the plate 13 and the water that is in that space will, because of capillary forces and surface tension, bridge the gap between the plates and be quickly sucked away by the suction pump. Even where the power to the pump is shut off before the water can be completely removed, the water bridging the gap be tween the plates tends to remain in place because of capillary forces and the very small amount of water that may seep through the perforated plate tends to evaporate before it can form globules sufficiently large to drip off.

Where the space between the plates 1 and 13 is filled with a porous material, such as a mat of glass fibers, then the interplate spacing can be larger without mate rially impeding the effectiveness of the cooling panel. It is important that the capillary passageways above the perforated plate have the ability to draw and hold the water. This ability can be assured by spacing the plates close enough together to cause the water to bridge the gap between the plates or if the plates are placed farther apart filling the space with a porous material.

It is apparent that the specific capillary structures utilized in the contruction of an efficient embodiment of the invention depend somewhat on whether a suction pump or other device is employed andthe amount of externally produced suction that is thus provided. Where a suction producing device is not employed, the capillary passages in the inner porous layer must not be too large as otherwise a satisfactory internal drawing force cannot be produced by the capillary or wick action of the inner porous layer. The employment of a suction pump is preferred as it permits the capillary system in the inner porous layer to be coarser, thus greatly increasing the ability of the panel to quickly remove the water condensate that forms on the exposed cold surface.

The suction pump may be connected to the discharge tube or conduit at any point along the tube, but preferably at the discharge end of the tube. However if the pump is located at the point where the discharge tube connects the panel then it should produce suction within the inner passageways in the panel and draw the water condensate from the exposed face of the panel into the panel and from thence pass the water into the discharge tube. This suction pump or pumping menas may for example be a small electrically driven pump or even an asperator type of suction producing means where the energy for producing the suction comes from pressurized water.

As the condensate water flows down the discharge tube, assuming the discharge tube does have a downward slope for a considerable distance, the weight of the column of water in the tube can produce a reduced pressure in the upper part of the tube. However it is still very desireable to have a separate means usch as an electrically driven suction pumping means for producing a reduced pressure within the panel. The electric suction pump produces suction within the panel very quickly whereas if one had to depend upon the downward flowing water within the discharge tube to produce suction one might have to wait a very long time for this suction to occur. In fact this suction might never occur for before it can occur there must be some sizeable force for drawing the water from the panel into the discharge tube. Thus in this application when the term suction pump or suction pumping or producing means is used it is intended to mean a separate suction pump or suction producing means and not simply the suction effect produced by the natural downward flow of condensate water in the discharge tube.

In general, the porous outer layer of a panel such as layer 5 or the porous plugs in the perforated plate 13 of FIG. 6 and 7 should be very fine grained and when wet will generally be impervious to an inflow of air. However, it can sometimes be desirable to have the layer 5 or the porous plugs 15 not quite so ultra-fine in porousity so that they become very slightly pervious to the passage of air and thus admit at least some air into the inner network of coarse capillary passageways. This small amount of admitted air aids in flushing out these inner coarse capillary passageways. With most of this water flushed out, there will be less possibility of structural damage being done to these passageways should any retained water in the passageways later freeze. Further, even if this retained water does not freeze there is the possibility that during periods when the cooling means for the cooling panel is turned off, fungi or molds or other microorganisms may grow in the wet or damp passageways and cause disagreeable odors. Also the discharge tube that leads from the cooling panel to the pump and thence to a discharge sink, may not be a simple straight downwards sloping tube but have loops and turns in it as it is led up and around through the partitions of a building. Some of these loops may cause the tubing to slope upwards instead of downwards. Thus, there can be large hydrostatic pressures in this discharge tube that necessitate a large and more powerful pump to produce the suction necessary to lift the water over a rise in the tubing.

If the column of water in the discharge tube is interspersed with bubbles of air so that short columns of water alternate with long columns of entrapped air, then the hydrostatic pressures in the discharge tube will be considerably reduced. For example, if the contents of a discharge tube consist of 10 percent by volume of water and 90 percent by volume of air, then the hydrostatic pressure of the water in the tube will be only 10 percent of what it would be if the contents were completely water. With this reduced hydrostatic head, the requirements of the discharge pump are much reduced. Further, when the cooling system with its discharge pump is shutoff, there will be no water remaining in the discharge tube to flow backward into the panel and drip on the floor or other area beneath the panel-- provided air has been introduced into the panel to flush out the water in the discharge tube. Even with a panel located on the ceiling of a room, there still can be many feet of discharge tubing that is located higher than the panel and which has the capacity to hold a considerable amount of water which can later flow back into the panel when the pump is shut off. Thus there are advantages in flushingout the water.

FIGS. 8, 9 and 10 depict a variation of a cooling panel in which the perforations in the perforated plate 21 having an exposed cold surface are not filled with a porous plug and the perforations 21A although small in diameter can still admit a small amount of air along with the condensate water. In the panel depicted in FIG. 8, a heat absorbing or cold plate 25 is cooled by a coolant which flows through tubes 2. The upper surface and the sides of the cold plate are thermally insulated by a heat insulative shield 3. The lower surface of the cold plate is closely adjacent to the perforated plate 21 having the perforations 21A. The lower surface of the cold plate has spacing protrusions which contact the perforated plate and partition the space between the two plates into long parallel passageways 22 as better shown in FIG. 9. The perforations in the perforated plate 21 may be formed by punching a fine pointed needle shaped punch through a soft zinc or other metal sheet having good thermal conductivity and preferably also having a hard white finish such as a suitable thin white plastic coating. This white plastic coating is desirable partly because of its esthetic eye appeal and partly because a bare metallic surface is a chemically unstable surface subject to oxidation and other types of corrosion which can very adversly affect its water retention properties. The plastic should be suitably chosen so as to be at least partly wettable by water. Also it should be roughened with fine emery paper or otherwise toothed" to provide a capillary surface that holds water and spreads it out-to cause the condensate water droplets that form on the surface to reach a perforation where the droplets are sucked away.

If the undersurface of a panel is coarsely toothed, for example through a sand blasting operation which produced deep crevices, then condensate water will flow laterally within the crevices towards the perforations.

Capillary attraction within the crevices is an important factor in this lateral flow. However, if the toothing on the undersurface is very fine, then very little water will move laterally within the actual crevices of the toothed layer. Rather the water, after filling the crevices, will tend to flow laterally just outside the crevices. This moving water will cling to the underside of the toothed layer but its flow, if there is any appreciable quantity of flow, will be mostly just outside the crevices rather than within the crevices. This type of flow can still be quite acceptable and does not detract from the importance of having a toothed surface-even a very finely toothed surface. Thus if a large drop of condensate water forms on the undersurface of a panel and this undersurface is finely toothed the edges of the drop will creep radially outwardly along the undersurface to spread the drop out along the undersurface. The fine toothing greatly facilitates this spreading out of the drop. When this flattened, spead-out drop reaches a perforation it is sucked away. If the undersurface of a panel were smooth, a large drop of condensate water on the undersurface would tend to ball upand drop off. To prevent these drops from falling, the perforations in a panel having a smooth undersurface must be quite closely spaced. With a capillary undersurface such as a coarsely or finely toothed undersurface the perforations can be spaced farther apart. This is one of the advantages of providing the undersurface of a panel with a capillary suface such as a toothed surface.

The insulation adjacent to the cold surface of the panel such as the insulation shown on the sides of the FIG. 8 panel, should preferably also have a toothed or porous surface so that any water that condenses on the insulation will spread out and smoothly run down to the cold surface where the water can be drawn away.

The FIG. 9 drawing of the panel shows only 36 holes and is intended to be only a schematic drawing. A practical panel might be quite large in area and have large numbers of perforated holes. These holes might be, for example, three-eighths inch apart depending on the degree of which the lower surface of the panel is toothed. After the punching operation, the innerside'2lB (FIG. 10) of the plate may be lightly sanded to smooth the jagged edges of the punched perforations. Then these edges may be electroplated with additional metal to reduce the size of the hole. In most punching operations, it is difficult to make the holes sufficiently fine. Thus, it is desirable to reduce their size by an electroplating operation. FIG. 10 shows a typical electroplated hole. The additional metal 21C that has been electroplated on the plate partly closes in the hole thus making it a much finer hole. Unless the holes in the cooling surface are unusually fine, excessive amounts of air will flow into the inner passageways and destroy the suction therein. When some air is introduced into the panel the inner passageways 22 may be thicker than usual to accommodate both the air and the condensate water. However, these inner passageways should, in general, not be thicker than a drop of water so that a water droplet in a passageway will span the thickness of the passageway and thus be readily sucked out of the passageway by the flow of air.

The passageway can be relatively wide but it is still considered a capillary? passageway where a large drop or mass of water spanning the passageway from one side ot the other clings to both sides and remains clinging rather than quickly collapsing and clinging to only one side of the passageway. Thus, a common soda straw used to suck in drops of ginger ale etc. from a glass is considered in this discussion a capillary" passageway because a large drop of ginger ale that has spanned across the straw remains spanned across the straw rather than collapsing the clinging only to one side of the straw. Thus, individual drops of ginger ale can be readily sucked up the straw.

If a passageway has a rectangular rather than a circular cross section, such as passageway 22, then for this passageway to be considered a capillary passageway a large drop of water should be able to span the passageway between the two closest walls and cling to both these opposing walls without collapsing and making contact with only one of the walls. A drop of water spanning the passageway can be more easily sucked away than a drop which does not contact both sides of the passageway. Furthermore, a drop of water may easily be joined by other drops to form a larger mass of water which readily spans across all four opposing walls of the passageway thus greatly facilitating the removal of this larger mass of water by suction. Although the fine holes in FIGS. 8, 9 and 10 are shown free of any porous plugs, they may be filled with a porous material provided the porous material is coarse enough to admit some air. The air admitted into the panel need not be admitted evenly through the various perforations or holes. If the holes farthest removed from the discharge end 23 (FIG. 9) of the panel, such as holes 21D, are large enough to admit some air into the panel and all the remaining holes are plugged with a finely porous material that when wet is impervious to air, then the air admitted through holes 21D will still be effective in flushing out the water from the inner passageways and from the exhaust tube 24 and in the process will reduce any undesirable hydrostatic water pressure in the exhaust tube.

The sucking of air and water simultaneously through a tiny perforation or the pores therein can result in an undesirable gurgling sound depending on the pressure gradients within the perforation, the size of the capillary passageway or passages within the perforation, the quantity of air admitted, etc; Much of this sound can be eliminated by sucking in the air at another point in the structure that is away from those areas where water is condensing. For example, if a small diameter hole were drilled through the insulation 3 at the side of the panel and into the inner passageway 22 and a thin air intake tube was inserted in this hole so that the tube extended from the inner passageway to a point that was outside the panel and preferably near the top of the panel then air would enter the inner passageway and quietly push along any water in the passageway toward the discharge tube. However, the air entering this tube at its entrance end near the top of the panel would be pure air unmixed with any water. Thus, there would be no gurgling sound taking place at the air intake orifice. This air intake tube should be quite fine in diameter and be preferably plugged with a finely porous material to reduce the amount of air entering the system. Only a very small amount of air is actually needed. Pure air unmixed with water that enters this air intake tube will upon emerging from the exit end of the tube slowly push water in the inner passageways toward the discharge tube 24. This mixing of the air and water in the inner passageways will normally be relatively quiet since no high velocity jets of air are involved. The exit end of the air intake tube may be located in a part of the inner passageway system that is at the opposite end of the panel from the discharge tube in which case it will flush water out of the inner passageways, or this exit end of the tube may be located closer or even directly next to the discharge tube 24 or even joining onto the discharge tube at or near the junction point of the discharge tube and the panel, in which case it will flush water out of the discharge tube but not out of the inner passageways. The entrance end of this air intake tube can be located at any point on the panel or away from the panel that is not excessively cold so as to be a condensation point for moisture. If the entrance end of this tube is near a wet region, this entrance to the tube should at least be protected against the water so that the entering air does not mix with the water to produce gurgling sounds. In any case, if air is introduced into a room air conditioning panel, it can be very desireable to employ some means for introducing the air quietly enough so as not to be objectionable.

Thus, there can be advantages in designing an air cooling structure that is very slightly pervious to the passage of air from the outside to the inside of the structure. This very small amount of air may be admitted through one or more of the perforations in the perforated plate 21 or the air may be admitted through small openings that are located elsewhere in the structure such as in the side of the cooling panel.

All of the various cooling panels discussed in this application can be made slightly pervious to the passage of air. Special openings can be constructed in the sides of the panels or at other convenient points to admit a small amount of air, or the very fine capillary network or layer on or near the exposed face of the cooling panel that is normally only pervious to water can be built with a few or even most of the fine capillary passageways slightly oversize so as to admit a very small amount of air. In speaking of a cooling panels perviousness to air, one is referring of course to a panel that has been in normal operation for a reasonable period of time so that the water that has condensed on its exposed surface has had a chance to wet arid seal all the fine pores that are sealable by the water. The suction pumping means should also of course be operated at its normal speed. Then the amount of air that leaks into the panel will be a measure of the perviousness of the panel to the passage of air.

During the on-of cycling of a cooling system, the suction pump may be programmed to operate at several different speeds other than zero speed. For example, just before the suction pump is shut off it may be operated at its highest speed to suck air into the system and cleanse the various passageways in the structure of as much water as possible. Thus, a cooling structure may be pervious to air when the suction pump is operating at its highest speed but not at its lower or intermediate speeds. In referring to a cooling structures perviousness to air or admission of air into the structure one is referring to the perviousness in that phase of the systems cycle in which the pores are wet and in which the suction pump, if the pump is programmed to operate at several different speeds, is operated at its higher speed. The structure may be pervious at lower pump speeds but it should at least be pervious at these higher speeds if the system is going to be pervious at all.

As mentioned previously an air cooling structure may have a special air intake opening, such as a small opening in the side of the structure, for admitting a very small amount of air into the structure. This special opening may be a very unobtrusive and casual opening. It is called a special opening only because it is not part of the regular porous outer layer or any of the regular perforations in a perforated plate when such a plate is used.

The spacing protrusions shown on the lower surface of the cold plate 25 may actually be part of the perforated plate 21 rather than the cold plate 25. Thus, a perforated plate having an exposed face for cooling the air need not necessarily be a very thin plate but instead might better be referred to as a relatively thin plate or simply a plate with enough thickness to permit portions of its upper side to be milled away to provide the necessary spacing protrusions. These protrusions will extend upwardly toward the cold source such as the cold plate 25. The lateral spaces between adjacent protrusions become drainage channels. Thus, a perforated plate may structurally incorporate within itself both a fine and coarse capillary layer or network.

In the FIG. 8 embodiment, there is depicted an example of several capillary systems cooperating with one another to produce an efficient water removal system. The toothed, easily cleanable, undersurface of the panel 20 constitutes the first capillary system. It causes the water that condenses on its surface to spread out and contact the fine perforated holes 21A. These perforated holes are capillary holes. They may or may not be plugged with a porous material but in any case they are capillary holes and constitute the second capillary system. The coarse inner passageways 22 consititute the third capillary system. These three capillary systems are all interconnected and through these systems,

water that condenses out on the lower surface flows along the first capillary system to the second where it is sucked up to the third system and from thence to the discharge tube. If the undersurface of the panel is smooth instead of toothed, then there will be but two capillary systems --the fine perforated holes being the first one and the coarse inner passageways the second one. Although a panel having three interconnecting capillary systems is preferable to a panel having only two, a panel having only two capillary systems can still be made to operate effectively provided the perforated holes are closely enough spaced to suck in the condensed water before such water drops off the panel.

Although it is desirable to have the thickness of the inner passageways no more than that of a large drop of water, it is even more desirable to have the thickness of these passageways smaller than this. A thinner passageway is usually adequate to carry the combined water and air, particularly if not much air is introduced into the system. Although the air may flush most of the water out of the inner passageways, it may not flush all the water out. The thinner the inner passageways, the less water there can be to remain behind in them and causes trouble after the cooling system is shut off.

In the FIG. 6 cooling panel the perforated plate 13 with its high thermal conductivity is actually also a heat absorbing plate. It readily absorbs heat and transmits this heat relatively rapidly up into the panel where it is quickly absorbed by the cooling tubes 2. In describing or referring to a cooling panel such as the FIG. 6 panel it is usually quite clear which plate one is referring to by the language used. For example, in speaking of a cooling panel such as the FIG. 6 panel as having a heat absorbing plate and also a perforated plate that is closely adjacent to the heat absorbing plate it is obvious that the heat absorbing plate is plate 1 and the perforated plate is plate 13. If one referred to a cooling panel as having a perforated heat absorbing plate then in the FIG. 6 cooling panel that plate would be the perforated plate 13. In the same way if one referred to a perforated heat absorbing plate in the FIG. 8 panel that plate would be the perforated plate 21.

A heat absorbing plate should have good thermal conductivity as would be the case if the plate were composed of aluminum or other metal. This plate may in some cooling panels constitute the outside face of the panel with the outer face of the heat absorbing plate being exposed to the air being cooled. If this plate is an aluminum plate then its exposed surface or face may be metallic aluminum. However, this outside face of the aluminum plate may be coated with a very thin layer of a paint or plastic. If this plastic layer is quite thin it will not unduly impede the flow of heat from the air into the aluminum plate. Since the air itself is such a very poor heat conductor there will not be much reduction in the heat absorbing efficiency of the cooling plate even when this plate is coated with a thin plastic layer. The thermal conductivity of the plastic although not nearly as good as that of the aluminum will still be considerably greater than that of the adjacent air. Therefore, in this application when one speaks of a heat absorbing plate or a heat absorbing and transmitting plate, and particularly if this plate has one of its faces exposed to the air to be cooled, it is to be understood that this exposed face of the plate may be coated with a thin layer of a material which is not as good a heat conductor as the main portion of the plate and a plate so coated will still be considered a heat absorbing plate. Thus, it is intended that a heat absorbing plate that has one of its faces exposed to the air being cooled may include a coated plate such as a plastic coated plate with the coating in the coated plate being the portion of the plate that is exposed to the air.

The words sheet and plate are used with their broad meanings in this application and can often mean the same thing. A plate is generally thought of as being thicker than a sheet. However a plate such as the plate 13 can be very thin so as to be sheet-like in appearance, yet it is still referred to as a plate. In the same way a sheet can be very thin or not quite so thin.

The inner coarse capillary layer of a cooling panel should normally be located in or between the cold plate and the outer fine grained porous layer such as in the embodiment of FIG. 4. However, a cooling panel may be designed in which the coarse capillary layer is on the opposite side of the cold plate from the fine grained porous layer. For this purpose the cold plate should be pierced or perforated with many small holes to permit water that condenses on the fine porous layer to be sucked up through the perforations in the cold plate to the coarse capillary layer on the other side of the cold plate. This water in the coarse capillary layer is then drawn off to the discharge tube as in the other panels.

In FIG. 11 is depicted an embodiment of a cooling panel that may be advantageously used in the midportions of a refrigerator as a horizontal shelf, for example. The panel comprises a top perforated plate 31 and a bottom perforated plate 32 having perforations 33. Both plates should have good thermal conductivity. In between these two plates are metallic cooling tubes 34 having a rectangular cross-section for carrying a cold refrigerating fluid. These cooling tubes are bonded to the two perforated plates to aid in providing good structural rigidity to the panel and also to increase the heat transfer characteristics of the panel. The panel may have high thermal resistant plastic end sections 35 which seal the ends of the panels. Soft rubber or other plyable pads 36 fill the interior spaces in the panel between the perforated plates and the cooling tubes. These pades which may be of a molded construction have long narrow passageways 37 molded into them. These passageways which run generally parallel to the cooling tubes are located between the perforations 33 as shown. The passageways 37 which will be called the inner passageways or drainage passageways or channels should all communicate with a suitable discharge conduit and suction producing means to suck water away from the panel.

When moisture in the air to be cooled condenses on the perforated plates it is drawn into the perforations and then along the interface between the inside surfaces of the perforated plates and the portions of the rubber pads in contact with the inside surfaces of the perforated plates until it reaches an inner passageway 37 where the water is sucked away. The surfaces of the rubber pads that are adjacent the inside surfaces of the perforated plates should be slightly toothed or rounghened to provide very fine capillary flow paths at the interfaces of the perforated plates and the rubber pads. The soft rubber pads should preferably be slightly oversize so as to press against the perforated plates. However they should not press so tightly that they destroy the fine capillary flow paths at the interface. One way of insuring against this occurrence is to thinly coat the surfaces of the rubber pad with a material that is harder than the rubber in the rubber pad. The surface of this harder material should of course also be finely toothed. Then even if the rubber pad presses quite strongly against the perforated plates the toothing in the harder coating material will not collapse. As an alternate to a coating a very thin sheet of a material that is harder than the rubber may be laminated to the surfaces of the rubber. In addition, if desired, this harder surface sheet may be finely porous throughout its thickness to add to the number of very fine lateral capillary pathways. However, the roughened or finely toothed surface of this laminated sheet or of the surface of the rubber pad itself, even if a harder coating or laminate is not used over the rubber pad, should in most cases be sufficient to supply the necessary fine lateral capillary pathways. The inside surfaces of the perforated plates can of course also be toothed or coated with a very thin layer of porous material to add to the fine lateral capillary pathway system.

Depending upon the manner in which the cooling tubes wind around inside the panel, it may be necessary to have the discharge conduit contact the panel at several points along the edges or sides of the panel so as to provide easy access to all the inner passageways 37. These inner passageways may of course be interconnected with one another near the edges of the panel where the discharge conduit contacts the panel to facilitate good communication between the inner passageways and the discharge conduit.

One of the advantages of the FIG. 11 panel is that is readily withstands the disruptive pressures of freezing water. Furthermore if any small food particles clog the fine capillary flow paths adjacent the perforations they can be rather readily flushed out. These fine capillary flow paths relate in function to the porous capillary plugs 15 of FIG. 7. Both of these types of fine capillary means impede the flow of air through the perforations. They may allow only a minute trickle of air to seep into the panel or they may block the air flow completely depending upon the fineness of the fine capillary passages. In the FIG. 7 panel the fine capillary means are mainly inside the perforations while in the FIG. 11 panel the fine capillary means are adjacent the perforations. In either case, they block the perforations with fine capillary means or members that impede the entry of air through the perforations. These fine capillary means should provide capillary pathways large enough of course to permit the passage of the condensate water through the perforations and to the inner passageways. However, the water in the very fine capillary pathways, because of the waters rather high surface tension, will either partially or completely seal the fine capillary pathways and thus block the passage of all or practically all the air depending upon the size and properties of the fine capillary pathways.

Although the FIG. 11 panel has perforated plates on both its upper and lower surfaces, it is of course obvious that this panel may be constructed with a perforated plate on only one of its faces. There may even be thermal insulation on its opposing face so that the panel may be advantageously used on the inside surfaces of a refrigerator compartment particularly on the ceiling of the refrigerator compartment. This panel with only one perforated plate, may, furthermore, be advantageously used on the walls of a room of a house but particularly on the ceiling of the room to cool and dehumidify the room.

In the FIG. 8 type of panel construction, a rubber pad such as is shown in FIG. 11 may also be used in the interpassageway spaces 22 to impede the flow of air through the perforations. The very fine lateral leakage paths between the rubber pad and perforated plate would provide the very fine capillary flow paths referred to in the FIG. 11 description. The long narrow passageways 37 in the rubber pad would then become the new inner passageways in the FIG. 8 panel. Even if there is no rubber pad in the spaces 22 of the FIG. 8 panel there should preferably at least be a very thin coating of a rubbery paint such as rubber latex on the inside surfaces of the inner passageways 22 to absorb the expansion forces of water when it freezes. This coating may be extremely thin but it can still greatly aid in preventing structural damage to the panel when any water within the panel freezes. In addition, where freezing water is a problem, any porous material used in the construction of a panel including any porous plugs used to plug the perforations in a perforated plate should preferably be constructed of a meterial having some resiliency to insure a longer useful life for the porous material. Sponge rubber and commercial cellulose sponges are examples of porous materials that are also plyable. With suitable manufacturing procedures the pores in these and other plyable materials can be made very small. As is known in the plastics arts many plastic types of materials including those having some resiliency can be made porous.

Thus, all the passageways within a cooling panel that come in contact with the condensate water should have some type of resilient construction such as a resilient wall construction. These passageways will be referred to as the water condensate conduction passageways". These passageways include, by way of example, the fine pores in the porous plugs 15, the fine capillary flow paths in the FIG. 11 panel between the rubber pads 36 and the inside surfaces of the perforated plates 31 and 32, as well as the larger drainage passages or channels 22 or 37. These passageways, furthermore, include the passageways in the fine and coarse porous layers 5 and 4, respectively, in the FIG. 1 panel and also the fine and coarse passageways in the FIG. 4 panel. Thus, the term internal water condensate conduction passageway is intended to be a broad term that includes all passageways in a cooling panel that come in contact with water condensate. A resilient wall construction is more necessary for some passageways than for others. Ideally, however, a resilient wall construction should be employed in all or at least most of the passageways of a cooling panel. As mentioned earlier, the soft rubber pads 36 may have a hard sheet that is less plyable than the rubber pads laminated to or otherwise in contact with the surface of the rubber pads. This type of construction still provides a resilient wall construction. The relatively hard sheet in contact with the surface of the rubber pads can itself be considered a resilient member because when the water condensate freezes, the hard sheet can move or give" by causing the rubber pads to compress. When the frozen condensate thaws, the rubber pads will decompress and the hard sheet will re turn to its original position against the perforated sheet. Also, the hard sheet, if flexible like a leaf spring, can flex and unflex when stressed and unstressed. Thus, the

freezing of water will not cause injury to the cooling panels employing this type of resilient construction.

The cooling panel shown in FIG. 11 illustrates another example of multiple capillary systems all parallel to one another and all cooperating with each other to achieve a superior water removal system. The perforations in the perforated plate constitute the first capillary layer or network. The very fine lateral capillary pathways at the interface of the perforated plate and the rubber pad comprise the second capillary system while the interpassageway network of relatively large drainage channels leading to the discharge conduit constitute the third capillary system. These capillary systems all communicate with each other; the first with the second, and the second with the third. Also, the three systems are in a layered configuration with the three layers all parallel to one another.

If the outside surface of the perforated plate were toothed then this toothed layer would constitute the first capillarylayer and there would then be a total of four capillary layers or systems, all parallel with one another and all communicating in the proper sequence with one another. EAch of these four capillary layers would be performing its own important function and contributing to the successful overall performance of the cooling panel.

A narrow or thin" passageway or channel in an air cooling panel will almost always be thin enough to be of capillary dimensions. However, it may under some circumstances, be moderately larger, such as for example in the situation, where something less than ideal operation is acceptable.

When a cooling panel is used within a refrigerator compartment to cool the compartment the moisture in the air within the compartment will almost always freeze upon condensing on the panel since the temperature of the panel is usually below freezing. Thus, the refrigerating fluid used to cool the panel should at suitable intervals be cycled off so that the panel can warm up enough to melt the frozen condensate water on its surface. Then, if the suction pump is also energized at this time, the melted condensate can be sucked into the panel and into the discharge tube. In addition, it is usually also desirableto supply heat to the panel during the defrost" portion of the cooling cycle so that even though the refrigerator compartment itself is below the freezing temperature, the frozen condensate on the panels surface will still melt and be sucked away. This heat may be supplied by electric heating coils within the panel or by heating instead of cooling the refrigerating fluid and passing the heated fluid through the cooling tubes in the panel. Thus, in this application, when it is stated that the condensate water is drawn into the panel and thence to the discharge tube, it is to be understood that there can be on-defrost" cycles in the operation of the cooling panel and that the moisture in the air may mostly condense on the panel during the cold on" portion of the cycle and then be withdrawn into the panel during the warm defrost portion of the cycle. The condensing of the moisture onto the panel and withdrawal of this condensed moisture into the panel need not occur simultaneously. The cooling panel in a refrigerator should be defrosted at suitable frequent intervals so that the frozen condensed moisture on the exposed face of the panel will not build up into a thick icy layer. If this layer becomes excessively thick then during the defrost periods when preferably some heat is supplied to the panel a thin layer of ice in intimate contact with the exposed face of the panel will melt and the remaining outer layer of still frozenice could conceiveably drop off the panel as large chunks. This is not the way the panel is intended to be operated. The entire purpose of the panel is to both cool the air and to absorb and remove water condensate on the panels surface before this condensate can drop off.

A cooling panel should, in most cases, be lOO percent effective in absorbing the condensate water on its surface before any of this water can drop off the panel. However, if there is an obvious imperfection in the panels construction or if a large piece of lint or large particle of food or other foreign object becomes attached to the panel or if the panel is otherwise soiled, a small amount of water may drop off the panel. Or, the main portion of the panel may operate in an ideal or near ideal manner while the corners or edges of the panel may be imperfect because the plastic edge pieces were not properly constructed. If a small amount of water falling from an imperfect panel can be tolerated then the panel should be considered an operable panel. Thus, when the statement is made that the perforations in the perforated sheet or plate of a cooling panel are so spaced or closely enough spaced to one another so that water which has condensed on the exposed face of the perforated plate is drawn into the perforations rather than dropping off the plate it should be understood that because of some imperfections in the panel or the rest of the cooling structure a small amount of water may, in some cases, drop off the perforated plate. However, this small amount of water that might drop off should be small compared to the large amount of water that is drawn into the panel and discharged through the discharge tube.

The amount of water dripping from a cooling panel that can be tolerated, depends in large measure, upon the environment in which the panel is used. For example, where the panel is used on the ceiling of a room near perfect operation is required in a commercial acceptable device in as much as most people will not tolerate much water dripping from the device. In other circumstances, as where the panel is used in a refrigerator, a modest amount of drippage may be tolerable and even be desirable where moisture is wanted, as over a vegetable bin.

Also, some very small drops of water may cling to the exposed face of a perforated plate, particularly if this exposed face is non-capillary in nature. These drops may be too small to extend themselves to a perforation and be sucked away, yet they are also too small and light to drop off the exposed face of the plate. They are therefore, essentially harmless.

A thin plastic detachable grid may be placed on the exposed surface of a cooling panel in a refrigerator compartment to prevent food packages etc. from freezing and sticking onto the panels surface.

In the literature there are described many kinds of air cooling and/or water condensing and removal or vapor liquifying and removal structures whose action depends upon all the air or other vapors being treated flowing through the structure. These structures have entrance ports and exit ports for the admission and discharge of the air or other vapor to be treated. Usually strong blowers and large ducts are employed with the ducts being connected to the above structures to insure that all the air or vapor being treated is guided up to and into the structure. The invention in this application concerns air cooling and water condensate removal structures that are of. the type in which the air to be cooled and dehumidified contacts the structure essentially only on its exterior side without flowing into the structure to any considerable degree so that substantially all of the air remains on the outside of the structure. The term without flowing into the structure to any considerable degree applies, of course, to those structures in which no air is admitted into the structure as well as other structures in which only a very small amount of the air to be cooled enters the structure.

In most applications the cooling panel should be flat. However, useful panels can be designed that have a curvature or are otherwise non-flat.

The term toothed or toothed layer or toothed surface when used in this application, is intended to be a broad term and to include grooved surfaces such as in a machinist file although the grooves may be deeper and more widely spaced then this. The grooves can be narrow while the spaces between the grooves can be relatively wide. The term also, of course, includes randomly or nonrandomly pitted layers or surfaces. A capillary layer or surface is intended to include both a porous layer or surface and also a toothed layer or surface. The toothing may for example be accomplished by sand blasting with fine abrasive particles, rubbing wit-h emory paper, mechanically grooving with sharp cutting tools or etching with chemicals. The porous layer or surface might, for example, be a thin coating of a porous paint or a thin coating or layer of an aerated portland cement mixture that hardens into a porous layer. 1

ln view of the various ways in which the invention can be embodied, it is not intended that the scope of the invention be restricted to the precise structures illustrated in the drawings or described in the exposition. Rather, it is intended that the scope of the invention be construed in accordance with the appended claims and that within that scope be included only those structures which in essence utilize the inventive concept here disclosed.

What is claimed is:

1. An air cooling and watercondensate removal structure of the type in which the air to be cooled contacts the structure on its exterior side but essentially does not flow into the structure so that substantially all of the air remains on the outside of the structure, said structure comprising a cooling panel having a cold outer capillary surface for cooling the adjacent air,

means to withdraw through the capillary surface water that condenses on said capillary surface from the adjacent air being cooled,

and said capillary surface having pores of a size that transmits through the surface the water that condenses on the surface but said pores blocking the transmission of most of the adjacent air being cooled.

2. An air cooling and water condensate removal structure according to claim 1 wherein the means to withdraw water from said capillary surface includes coarse capillary passageways that empty into a discharge conduit,

and a suction pumping means communicating with the discharge conduit for producing at least a mild vacuum within the coarse capillary passageways in the panel whereby condensate water is readily pulled into the panel and discharged into the discharge conduit.

3. An air cooling and water condensate removal structure comprising:

a perforated heat absorbing plate having one face exposed to the air being cooled, the plate being perforated with many separated holes,

means for cooling the perforated heat absorbing plate,

coarse drainage channels on the reverse non-exposed face of the perforated heat absorbing plate to remove water condensate drawn through the perforations from the outside exposed face of the perforated heat absorbing plate on which moisture from the cooled air has condensed,

and a discharge conduit communicating with the drainage channels to remove condensate water therefrom.

4. An air cooling and water condensate removal structure of the type in which the air to be cooled contacts the structure essentially only on its exterior surface without flowing into the structure to any considerable degree so that substantially all of the air remains on the outisde of the structure, said structure comprising:

a heat absorbing plate having a coarse capillary network of thin grooves on its face,

a material containing fine pores bridging the grooves at the face of the plate thereby producing a network of covered coarse capillary passageways in the heat absorbing plate, the passageways being bounded at the face side of the plate by the porous material,

the face of the plate presenting an exposed surface on which moisture from the cooled air condenses and is drawn into the porous material,

a discharge conduit communicating with the network of grooves for removing the condensate entering the grooves through the porous material,

and means to cool the heat absorbing plate, said means being separate from the means for removing water condensate from the panel.

5. The air cooling and water condensate removal structure according to claim 4 further including:

a suction pumping means comunicating with the discharge conduit for applying at least a mild suction to the coarse capillary passageways so that condensate water can readily be drawn into the coarse capillary passageways and discharged into the discharge conduit.

6. The air cooling and water condensate removal structure according to claim 5 wherein:

the material containing the fine pores is a perforated sheet in contact with and covering the face of heat absorbing plate, the perforated sheet having many small perforations with the perforations being so spaced that water which has condensed on the out- I side surface of the perforated sheet tends to be drawn into the perforations rather than dropping off the perforated sheet.

7. The air cooling and water condensate removal structure according to claim 6 wherein:

the exposed face of the perforated sheet has a capillary surface to facilitate the spreading of condensate laterally toward the perforations.

8. The air cooling and water condensate removal structure according to claim 6, further including:

blocking members associated with the perforations in the perforated sheet for blocking the perforations, said members providing small capillary passageways whose size is smaller than that of the unblocked perforations whereby the resistance to the passage of air through the perforations is increased.

9. The air cooling and water condensate removal structure according to claim 5, further including:

a thin finely textured porous layer on the exposed face of the heat absorbing plate to facilitate the spreading of condensate laterally towards the grooves.

10. The air cooling and water condensate removal structure according to claim 5, wherein:

the exposed face of the heat absorbing plate is toothed to facilitate the spreading of condensate laterally toward the grooves.

11. The air cooling and water condensate removal structure according to claim 5, including:

thermal insulating means along the sides of the heat absorbing plate, and capillary means associated with the insulating means to aid in removing the water that has condensed on the sides of the structure so that this water is drawn into the structure rather than dropping off the structure.

12. The air cooling and water condensate removal structure according to claim 5 wherein:

said structure is very slightly pervious to the admittance of air into the structure with the admitted air being discharged along with the water condensate in the discharge conduit.

13. The air cooling and water condensate removal structure according to claim 5, wherein:

at least a portion of the material containing fine pores bridging the grooves is very slightly pervious to the passage of air.

14. The air cooling and water condensate removal structure according to claim 5, further including:

one or more small openings in the structure other than the pores in the material containing five pores for admitting a small amount of air into the structure.

15. The air cooling and water condesnsate removal structure according to claim 5, wherein:

at least some of the water condensate conduction passageways in the heat absorbing plate have resilient walls as a protection against the disruptive forces of freezing water.

16. The air cooling and water condensate removal structure according to claim 5 wherein:

the material containing the fine pores includes a resilient material in its construction as a protection against the disruptive forces of freezing water.

17. An air cooling and water condensate removal structure of the type in which the air to be cooled contacts the structure essentially only on its exterior surface without flowing into the structure to any considerable degree so that substantially all of the air re mains on the outside of the structure, said structure comprising:

a heat absorbing plate,

means for cooling the heat absorbing plate,

a coarse porous layer adjacent to and covering the broad face of the heat absorbing plate, 

1. An air cooling and water condensate removal structure of the type in which the air to be cooled contacts the structure on its exterior side but essentially does not flow into the stRucture so that substantially all of the air remains on the outside of the structure, said structure comprising a cooling panel having a cold outer capillary surface for cooling the adjacent air, means to withdraw through the capillary surface water that condenses on said capillary surface from the adjacent air being cooled, and said capillary surface having pores of a size that transmits through the surface the water that condenses on the surface but said pores blocking the transmission of most of the adjacent air beeing cooled.
 2. cooling means to cool the panel whereby heat from the panel''s outer exposed face flows inwardly into the panel leaving the outer exposed face cold, the cooling means being separate from the water removal means,
 2. An air cooling and water condensate removal structure according to claim 1 wherein the means to withdraw water from said capillary surface includes coarse capillary passageways that empty into a discharge conduit, and a suction pumping means communicating with the discharge conduit for producing at least a mild vacuum within the coarse capillary passageways in the panel whereby condensate water is readily pulled into the panel and discharged into the discharge conduit.
 3. An air cooling and water condensate removal structure comprising: a perforated heat absorbing plate having one face exposed to the air being cooled, the plate being perforated with many separated holes, means for cooling the perforated heat absorbing plate, coarse drainage channels on the reverse non-exposed face of the perforated heat absorbing plate to remove water condensate drawn through the perforations from the outside exposed face of the perforated heat absorbing plate on which moisture from the cooled air has condensed, and a discharge conduit communicating with the drainage channels to remove condensate water therefrom.
 3. and a discharge conduit communicating with the inner capillary system for removing from the panel the water condensate that enters the inner capillary system from the outer capillary system.
 4. An air cooling and water condensate removal structure of the type in which the aiir to be cooled contacts the structure essentially only on its exterior surface without flowing into the structure to any considerable degree so that substantially all of the air remains on the outisde of the structure, said structure comprising: a heat absorbing plate having a coarse capillary network of thin grooves on its face, a material containing fine pores bridging the grooves at the face of the plate thereby producing a network of covered coarse capillary passageways in the heat absorbing plate, the passageways being bounded at the face side of the plate by the porous material, the face of the plate presenting an exposed surface on which moisture from the cooled air condenses and is drawn into the porous material, a discharge conduit communicating with the network of grooves for removing the condensate entering the grooves through the porous material, and means to cool the heat absorbing plate, said means being separate from the means for removing water condensate from the panel.
 5. The air cooling and water condensate removal structure according to claim 4 further including: a suction pumping means comunicating with the discharge conduit for applying at least a mild suction to the coarse capillary passageways so that condensate water can readily be drawn into the coarse capillary passageways and discharged into the discharge conduit.
 6. The air cooling and water condensate removal structure according to claim 5 wherein: the material containing the fine pores is a perforated sheet in contact with and covering the face of heat absorbing plate, the perforated sheet having many small perforations with the perforations being so spaced that water which has condensed on the outside surface of the perforated sheet tends to be drawn into the perforations rather than dropping off the perforated sheet.
 7. The air cooling and water condensate removal structure according to claim 6 wherein: the exposed face of the perforated sheet has a capillary surface to facilitate the spreading of condensate laterally toward the perforations.
 8. The air cooling and water condensate removal structure according to claim 6, further including: blocking members associated with the perforatIons in the perforated sheet for blocking the perforations, said members providing small capillary passageways whose size is smaller than that of the unblocked perforations whereby the resistance to the passage of air through the perforations is increased.
 9. The air cooling and water condensate removal structure according to claim 5, further including: a thin finely textured porous layer on the exposed face of the heat absorbing plate to facilitate the spreading of condensate laterally towards the grooves.
 10. The air cooling and water condensate removal structure according to claim 5, wherein: the exposed face of the heat absorbing plate is toothed to facilitate the spreading of condensate laterally toward the grooves.
 11. The air cooling and water condensate removal structure according to claim 5, including: thermal insulating means along the sides of the heat absorbing plate, and capillary means associated with the insulating means to aid in removing the water that has condensed on the sides of the structure so that this water is drawn into the structure rather than dropping off the structure.
 12. The air cooling and water condensate removal structure according to claim 5 wherein: said structure is very slightly pervious to the admittance of air into the structure with the admitted air being discharged along with the water condensate in the discharge conduit.
 13. The air cooling and water condensate removal structure according to claim 5, wherein: at least a portion of the material containing fine pores bridging the grooves is very slightly pervious to the passage of air.
 14. The air cooling and water condensate removal structure according to claim 5, further including: one or more small openings in the structure other than the pores in the material containing five pores for admitting a small amount of air into the structure.
 15. The air cooling and water condesnsate removal structure according to claim 5, wherein: at least some of the water condensate conduction passageways in the heat absorbing plate have resilient walls as a protection against the disruptive forces of freezing water.
 16. The air cooling and water condensate removal structure according to claim 5 wherein: the material containing the fine pores includes a resilient material in its construction as a protection against the disruptive forces of freezing water.
 17. An air cooling and water condensate removal structure of the type in which the air to be cooled contacts the structure essentially only on its exterior surface without flowing into the structure to any considerable degree so that substantially all of the air remains on the outside of the structure, said structure comprising: a heat absorbing plate, means for cooling the heat absorbing plate, a coarse porous layer adjacent to and covering the broad face of the heat absorbing plate, a fine porous outere layer disposed upon and covering the coarse porous layer, the outer layer having an exposed surface on which moisture from the cooled air condenses and is drawn into the layer, a discharge conduit communicating with the coarse porous layer for removing water therefrom, and the means for cooling the heat absorbing plate being separate from the water removal means.
 18. The air cooling and water condensate removal structure according to claim 17 and including: a suction pumping means communicating with the discharge conduit for drawing the water out of the coarse porous layer whereby condensate water on the exposed surface of the fine porous layer is readily drawn into the coarse porous layer and discharged into the discharge conduit.
 19. The air cooling and water condensate removal structure according to claim 17, further comprising: a water drainage channel at the margin of the coarse porous layer, the drainage channel being thicker than the coarse porous layer and being filled with a coarse porous material, and the discharge conduit communiCating with the coarse porous layer via the water drainage channel, and a water impervious wall being part of the structure for confining the water in the drainage channel.
 20. An air cooling and water condensate removal structure of the type in which air to be cooled contacts the structure essentially only on its exterior surface without flowing into the structure to any considerable degree so that substantially all of the air remains on the outside of the structure, said structure comprising: a heat absorbing plate, means for cooling the heat absorbing plate, a porous layer disposed upon the broad face of the heat absorbing plate, and said layer having an exposed outer surface on which moisture from the cooled air condenses and is drawn into the layer, a network of coarse capillary drainage tunnels in the porous layer to drain the condensate water from the porous layer, a discharge conduit communicating with the network of drainage tunnels for removing water therefrom, and the means for cooling the heat absorbing plate being separate from the water removal means.
 21. The air cooling and water condensate removal structure according to claim 20, further comprising: a suction pumping means communicating with the discharge conduit for drawing the water out of the drainage tunnels whereby condensate water on the exposed surface of the porous layer is readily drawn through the porous layer and into the drainage tunnels and discharged into the discharge conduit.
 22. The air cooling and water condensate removal structure according to claim 21, wherein: the porous layer is covered on its outer surface by a very thin layer having pores therein which are finer than the pores in the covered porous layer.
 23. The air cooling and water condensate removal structure according to claim 21, wherein: the exposed outer surface of the porous layer being a sheet having perforations.
 24. The air cooling and water condensate removal structure according to claim 23, wherein: the perforations in the perforated sheet are so spaced that water which has condensed on the perforated sheet tends to be drawn into the perforations rather than dropping off of the perforated sheet.
 25. The air cooling and water condensate removal structure according to claim 21, further including: thermal insulation along the sides of the heat absorbing plate, and capillary means associated with the thermal insulation to aid in removing the water that has condensed on the sides of the structure so that this water is drawn into the structure rather than dropping off the structure.
 26. The air cooling and water condensate removal structure according to claim 24, wherein: the perforations are plugged by a porous material.
 27. The air cooling and water condensate removal structure according to claim 21, wherein: at least some of the water condensate conduction passageways have resilient walls as a protection against the disruptive forces of freezing water.
 28. The air cooling and water condensate removal structure according to claim 21, wherein: some of the pores in the porous material over the face of the heat absorbing plate are very slightly pervious to the passage of air so that a very small amount of air is admitted into the drainage tunnels.
 29. The air cooling and water condensate removal structure according to claim 21, further including: at least one special air intake opening for admitting a very small amount of air into the structure.
 30. An air cooling and water condensate removal structure of the type in which the air to be cooled contacts the structure essentially only on its exterior surface without flowing into the structure to any considerable degree so that substantially all of the air remains on the outside of the structure, said structure comprising: a heat absorbing plate having one of its faces exposed to the air to be cooled, the plate having many small perforations in its exposed face, means for cooling the heat absorbing plate, a network of thin drainage channels behind the exposed face of the plate, the channels communicating with the perforations to permit removal of the water condensate drawn through the perforations from the outside exposed face of the plate on which moisture from the cooled air has condensed, a discharge conduit communicating with the thin drainage channels and leading to a drainage point away from the panel, the perforations in the heat absorbing plate being so spaced that water which has condensed on the exposed face of the heat absorbing plate tends to be drawn into the perforations rather than dropping off the plate, and the means for cooling the heat absorbing plate being separate from the water removal means.
 31. An air cooling and water condensate removal structure according to claim 30, further including: a suction pumping means communicating with the discharge conduit for producing a reduced pressure in the drainage channels whereby condensate water is readily drawn into the drainage channels and discharged into the discharge conduit.
 32. An air cooling and water condensate removal structure according to claim 31 wherein: the drainage channels are capillary passageways.
 33. An air cooling and water condensate removal structure according to claim 31 wherein the outer surface of the perforated heat absorbing plate is toothed, the toothed outer surface being a capillary surface which aids in spreading out the water condensate on the outer surface whereby the water more readily reaches a perforation in the perforated heat abosrbing plate and is drawn away.
 34. An air cooling and water condensate removal structure according to claim 31, further including: a thin, fine porous outer layer disposed upon and covering the outer surface of the perforated heat absorbing plate, the outer layer having an exposed surface on which moisture from the cooled air condenses and is drawn into the layer.
 35. An air cooling and water condensate removal structure according to claim 31, further including: thermal insulating means insulating the reverse face of the heat absorbing plate.
 36. An air cooling and water condensate removal structure according to claim 31, further comprising: thermal insulation along the sides of the heat absorbing plate, and capillary means associated with the thermal insulation to aid in removing the water that has condensed on the sides of the structure so that this water is drawn into the structure rather than dropping off the structure.
 37. An air cooling and water condensate removal structure according to claim 31, further including: blocking members associated with the perforations in the perforated heat absorbing plate for blocking the perforations, said members providing small capillary passageways whose size is smaller than that of the unblocked perforations whereby the resistance to the passage of air into the structure is increased.
 38. An air cooling and water condensate removal structure according to claim 37, wherein: the blocking members are resilient for protection against the disruptive forces of freezing water.
 39. An air cooling and water condensate removal structure according to claim 37, wherein: the blocking members are porous capillary members plugging the perforations in the perforated heat absorbing plate.
 40. An air cooling and water condensate removal structure according to claim 37, wherein: the blocking members are disposed at the discharge ends of the perforations.
 41. An air cooling and water condensate removal structure according to claim 40 wherein: the blocking members are resilient members that press against the discharge end edge regions of the perforations.
 42. An air cooling and water condensate removal structure according to claim 31, wherein: at least some of the water condensate conduction passageways have resilient walls as a protection against the disruptive forces of freezing Water.
 43. An air cooling and water condensate removal structure according to claim 31, wherein: the structure is very slightly pervious to the admittance of air into the structure with the admitted air being discharged along with the water condensate in the discharge conduit.
 44. An air cooling and water condensate removal structure according to claim 31, wherein: one of more of the perforations admit a very small amount of air into the panel.
 45. An air cooling and water condensate removal structure according to claim 31, further including: at least one special air intake opening for admitting a very small amount of air into the structure.
 46. An air cooling and water condensate removal structure of the type in which the air to be cooled contacts the structure essentially only on its exterior surface without flowing into the structure to any considerable degree so that substantially all of the air remains on the outside of the structure, said structure comprising: a heat absorbing plate, means for cooling the heat absorbing plate, a perforated plate having many small perforations, the perforated plate being closely adjacent to and covering the broad face of the heat absorbing plate thereby providing a thin passageway space between the two plates, a discharge conduit communicating with the thin passageway space between the plates to remove water condensate drawn through the perforations into the thin passageway space between the plates from the outside exposed face of the perforated plate on which moisture from the cooled air has condensed, the perforations in the perforated plate being so spaced that water which has condensed on the outside surface of the perforated plate tends to be drawn into the perforations rather than dropping off of the perforated plate, and the means for cooling the heat absorbing plate being separate from the water removal means.
 47. The air cooling and water condensate removal structure according to claim 46, further including suction pumping means communicating with the discharge conduit for producing a reduced pressure in the thin passageway space between the plates whereby condensate water is readily drawn into the thin passageway space and discharged into the discharge conduit.
 48. The air cooling and water condensate removal structure according to claim 47, further including: spacing means interposed between the heat absorbing plate and the perforated plate, the spacing means aiding the transfer of heat from the perforated plate to the heat absorbing plate.
 49. The air cooling and water condensate removal structure according to claim 48 in which the spacing means are actually a part of at least one of the plates.
 50. The air cooling and water condensate removal structure according to claim 47, wherein: the thin passageway space between the plates constitutes capillary passageways.
 51. The air cooling and water condensate removal structure according to claim 47, wherein: the outer surface of the perforated plate is toothed, the toothed outer surface being a capillary surface which aids in spreading out the water that has condensed on the outer surface whereby the water more readily reaches a perforation in the perforated plate and is drawn away.
 52. The air cooling and water condensate removal structure according to claim 47, further comprising: a thin, finely textured, porous outer layer disposed upon and covering the outer surface of the perforated plate, the outer layer having an exposed surface on which moisture from the cooled air condenses and is drawn into the layer.
 53. The air cooling and water condensate removal structure according to claim 47, further including: a layer of porous material filling the space between the plates.
 54. The air cooling and water condensate removal structure according to claim 47, further including: blocking members associated with the perforations for blocking the perforations in the perforated plAte, said members providing small capillary passageways whose size is smaller than that of the unblocked perforations whereby the resistance to the passage of air into the structure is increased.
 55. The air cooling and water condensate removal structure according to claim 54, wherein: the blocking members are resilient as a protection against the disruptive forces of freezing water.
 56. The air cooling and water condensate removal structure according to claim 54, wherein: said blocking members are composed of a porous capillary material which plugs the perforations.
 57. The air cooling and water condensate removal structure according to claim 56, wherein: the porous blocking members have enlarged heads that bridge the gap between the plates.
 58. The air cooling and water condensate removal structure according to claim 54, wherein: the blocking members contact the inside surface of the perforated plate adjacent the perforations thereby providing very fine capillary passageways in a generally lateral direction between the inside surface of the perforated plate and the blocking members in contact with the perforated plate, and said fine capillary passageways communicating with the thin passageway space between the perforated plate and the heat absorbing plate.
 59. The air cooling and water condensate removal structure according to claim 47, further including: thermal insulation along the sides of the perforated plate, and capillary means associated with the thermal insulation to aid in removing the water that has condensed on the sides of the structure so that this water is drawn into the structure rather than dropping off the structure.
 60. An air cooling and water condensate removal structure according to claim 47, wherein: at least some of the water condensate conduction passageways in the panel have resilient walls as a protection against the disruptive forces of freezing water.
 61. An air cooling and water condensate removal structure according to claim 47, wherein: one or more of the perforations is at least slightly pervious to the admittance of air into the structure.
 62. An air cooling and water condensate removal structure according to claim 47, further including: at least one special air intake opening for admitting a very small amount of air into the structure.
 63. An air cooling and water condensate removal structure of the type in which the air to be cooled contacts the structure essentially only on its exterior surface without flowing into the structure to any considerable degree so that substantially all of the air remains on the outside of the structure, said structure comprising:
 64. The air coolIng and water condensate removal structure according to claim 63, further including: a suction pumping means communicating with the discharge conduit for drawing the water out of the inner capillary system whereby condensate water on the exposed face of the panel is readily drawn into the inner capillary system and discharged into the discharge conduit.
 65. The air cooling and water condensate removal structure according to claim 64, wherein: the exposed outer face of the panel is a sheet having perforations therein.
 66. The air cooling and water condensate removal structure according to claim 65, wherein: the perforations in said sheet are so spaced that water which has condensed on the sheet tends to be drawn into the perforations rather than dropping off the sheet.
 67. The air cooling and water condensate removal structure according to claim 64, wherein: at least some of the capillary passageways in the panel have resilient walls as a protection against the disruptive forces of freezing water.
 68. The air cooling and water condensate removal structure according to claim 64, further including: thermal insulation along the sides of the panel and capillary means associated with the insulation to aid in removing the water that has condensed on the sides of the panel so that this water is drawn into the panel rather than dropping off the panel.
 69. The air cooling and water condensate removal structure according to claim 64, wherein: at least some of the capillary passageways in the outer capillary system are very slightly pervious to the passage of air so that a very small amount of air is admitted into the inner capillary system.
 70. The air cooling and water condensate removal structure according to claim 64, further including: at least one special air intake opening for admitting a very small amount of air into the structure.
 71. The air cooling and water condensate removal structure according to claim 63, further including: at least a third broad capillary water removal conduction system that is parallel and coextensive with said inner and outer capillary systems and located between these two systems with the passageways of the outer capillary system interconnecting with the passageways of the middle capillary system and the passageways of the middle capillary system interconnecting with the passageways of the inner capillary system, and the passageways of the middle capillary system being finer than the passageways of the inner capillary system.
 72. The air cooling and water condensate removal structure according to claim 71, further including: a suction pumping means communicating with the discharge conduit for drawing the water out of the inner capillary system whereby condensate water on the exposed face of the panel is readily drawn into the inner capillary system and discharged into the discharge conduit.
 73. The air cooling and water condensate removal structure according to claim 72, wherein: the exposed outer face of the panel is a sheet having perforations therein, the perforations being so spaced that water which has condensed on the sheet tends to be drawn into the perforations rather than dropping off the sheet.
 74. The air cooling and water condensate removal structure according to claim 72, wherein: at least some of the capillary passageways in the panel have resilient walls as a protection against the disruptive forces of freezing water.
 75. The air cooling and water condensate removal structure according to claim 72, further including: thermal insulation along the sides of the panel and capillary means associated with the insulation to aid in removing the water that has condensed on the sides of the panel so that this water is drawn into the panel rather than dropping off the panel.
 76. The air cooling and water condensate removal structure according to claim 72, wherein: at least some of the passageways in the outer and middle capillary water removal condUction systems are pervious to the passage of air so that a very small amount of air is admitted into the inner capillary system.
 77. The air cooling and water condensate removal structure according to claim 72, further including: at least one special air intake opening for admitting a very small amount of air into the structure.
 78. An air cooling and water condensate removal structure according to claim 63, wherein: at least a portion of the discharge conduit extends to a considerable height above the panel and further including means including suction pumping means communicating with the discharge conduit for drawing water out of the inner capillary system and causing this water to flow into the discharge conduit and to continue this flow up the considerable distance that the discharge conduit extends above the panel while simultaneously maintaining no more than a mild vacuum in the inner capillary system, said mild vacuum as measured in inches of water being less than the distance in inches that the discharge conduit extends above the panel.
 79. An air cooling and water condensate removal structure according to claim 30, wherein: at least a portion of the discharge conduit extends to a considerable height above the heat absorbing plate and further including means including suction pumpings means communicating with the discharge conduit for drawing water out of the drainage channels and causing this water to flow into the discharge conduit and to continue this flow up the considerable distance that the discharge conduit extends above the heat absorbing plate while simultaneously maintaining no more than a mild vacuum in the drainage channels, said mild vacuum as measured in inches of water being less than the distance in inches that the discharge conduit extends above the heat absorbing plate. 